The present invention relates to machinery for manufacturing glass containers and specifically to an I.S. (individual section) machine which processes a gob of molten glass, in a two stage process, into a glass bottle.
Each section of an I.S. machine has a blank station including a blank mold and a blow station including a blow mold. To form a bottle, a molten gob is loaded into a blank mold and formed into a parison. The parison is then transferred to the blow mold of the blow station where the parison is formed into the finished container. When both the parison and container are formed with pressurized air, this two stage process is referred to as a blow and blow process. In such a blow and blow process, the molten gob is dropped into a blank mold which is open at the top. A baffle is lowered onto the top of the mold to close the mold and air is introduced under pressure (xe2x80x9csettle airxe2x80x9d) through the baffle to force the mold into the bottom most portion of the blank mold which will form the threaded top portion of a container. At the same time a vacuum will be applied at the bottom of the blank mold to draw the gob into the threaded portion of the mold. When the molten glass fills the threaded portion of the mold, counter blow air is applied from the bottom of the mold to blow the gob into the parison.
This gob forming process is controlled by solenoid operated air pilot valves operated by a timing control. In one case the counter blow and vacuum use separate valves connected together so that the vacuum flow is through the counter blow valve and the exhaust must flow through both valves to atmosphere. It is a disadvantage to have the valves for counter blow and vacuum arranged so that the vacuum, heated by the hot gob, can flow through the counter blow valve heating it up sufficiently to cause sluggish operation. In another case, a single valve is used for both counter blow and vacuum having a center position where all ports are blocked and a second valve, integrated with the main valve, is activated for exhaust when the main valve is in the center position. It is a disadvantage to have the exhaust flow through a number of valves thereby restricting airflow.
Other objects and advantages of the present invention will become apparent from the following portion of this specification ad from the accompanying drawings which illustrate in accordance with the mandate of the patent statutes a presently preferred embodiment incorporating the principles of the invention.